linux_like: Unify statx definitions

[neuschaefer]

Description

The statx system call and corresponding constants are defined by the Linux kernel and don't depend on the libc or architecture. The only difference is whether a libc exports the statx syscall wrapper or not.

We can thus unify the statx definitions for all Linux "like" platforms: GNU (glibc), Android (bionic), and (in a later commit) musl.

The statx struct is in a separate file because the style check doesn't allow multiple s! macros in one file, and #[cfg()] doesn't work in s!.

Plain u64 (or uint64_t in C) can't be used for the statx fields because bionic defines them as __u64, and provides incompatible definitions of uint64_t and __u64.

Sources

none

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI (failed due to unrelated error, linux/errqueue.h)

[rustbot]

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